src/python/importer.py

   1 # Copyright (c) 2008 The Hewlett-Packard Development Company
   2 # All rights reserved.
   3 #
   4 # Redistribution and use in source and binary forms, with or without
   5 # modification, are permitted provided that the following conditions are
   6 # met: redistributions of source code must retain the above copyright
   7 # notice, this list of conditions and the following disclaimer;
   8 # redistributions in binary form must reproduce the above copyright
   9 # notice, this list of conditions and the following disclaimer in the
  10 # documentation and/or other materials provided with the distribution;
  11 # neither the name of the copyright holders nor the names of its
  12 # contributors may be used to endorse or promote products derived from
  13 # this software without specific prior written permission.
  14 #
  15 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  16 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  17 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  18 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  19 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  20 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  21 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  25 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26
  27 from __future__ import print_function
  28 from __future__ import absolute_import
  29
  30 # Simple importer that allows python to import data from a dict of
  31 # code objects.  The keys are the module path, and the items are the
  32 # filename and bytecode of the file.
  33 class CodeImporter(object):
  34     def __init__(self):
  35         self.modules = {}
  36
  37     def add_module(self, filename, abspath, modpath, code):
  38         if modpath in self.modules:
  39             raise AttributeError("%s already found in importer" % modpath)
  40
  41         self.modules[modpath] = (filename, abspath, code)
  42
  43     def find_module(self, fullname, path):
  44         if fullname in self.modules:
  45             return self
  46
  47         return None
  48
  49     def load_module(self, fullname):
  50         # Because the importer is created and initialized in its own
  51         # little sandbox (in init.cc), the globals that were available
  52         # when the importer module was loaded and CodeImporter was
  53         # defined are not available when load_module is actually
  54         # called. Soooo, the imports must live here.
  55         import imp
  56         import os
  57         import sys
  58
  59         try:
  60             mod = sys.modules[fullname]
  61         except KeyError:
  62             mod = imp.new_module(fullname)
  63             sys.modules[fullname] = mod
  64
  65         try:
  66             mod.__loader__ = self
  67             srcfile,abspath,code = self.modules[fullname]
  68
  69             override = os.environ.get('M5_OVERRIDE_PY_SOURCE', 'false').lower()
  70             if override in ('true', 'yes') and  os.path.exists(abspath):
  71                 src = open(abspath, 'r').read()
  72                 code = compile(src, abspath, 'exec')
  73
  74             if os.path.basename(srcfile) == '__init__.py':
  75                 mod.__path__ = fullname.split('.')
  76                 mod.__package__ = fullname
  77             else:
  78                 mod.__package__ = fullname.rpartition('.')[0]
  79             mod.__file__ = srcfile
  80
  81             exec(code, mod.__dict__)
  82         except Exception:
  83             del sys.modules[fullname]
  84             raise
  85
  86         return mod
  87
  88 # Create an importer and add it to the meta_path so future imports can
  89 # use it.  There's currently nothing in the importer, but calls to
  90 # add_module can be used to add code.
  91 import sys
  92 importer = CodeImporter()
  93 add_module = importer.add_module
  94 sys.meta_path.append(importer)